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Unsegmented Worms
PHYLUM
NEMATODA
Roundworms
….the roundworms
Taxonomy
Kingdom: Animalia
Phylum: Nematoda
Class:
Secernentea
Adenophorea
Phylum Nematoda Vocab
1. parthenogenesis
3. Hookworm *
5. Pinworm*
7. Elephantiasis
9. cloaca
2. cuticle
4. trichinosis
6. filarial worm*
8. vermiform
10. Microfilaria
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1. PARTHENOGENESIS- modified form of sexual reproduction by the
development of a gamete without fertilization
2. CUTICLE- noncellular, protective organic layer secreted by the external
epithelium (hypodermis) of many invertebrates
3. HOOKWORM- (New World or American Hookworm) Necator americanus;
found in southern US; adults live in small intestine
4. TRICHINOSIS- caused by (the porkworm) Trichinella spiralis larvae; get
from eating undercooked meat; characterized by muscular pain, fever,
edema (swelling), & other symptoms
5. PINWORM- Enterobius vermicularis; most common roundworm parasites
in the US
6. FILARIAL WORM- Wuchereria spp.; elongate, threadlike nematodes
that live in the lymphatic system, where they block the vessels
7. ELEPHANTIASIS- a chronic filarial disease most commonly occurring in
the tropics due to the infection of lymphatic vessels with the nematode
Wuchereria spp.
8. VERMIFORM- resembling a worm in shape; long and slender
9 . CLOACA- a common opening for excretory, digestive, & reproductive
systems
10. MICROFILARIA- the prelarval stage of filarial worms; found in the
blood of humans and the tissues of the vector (carrier)
Characteristics
•Pseudocoelomates- big
advancement….
why?
Characteristics cont
• Most small, many are microscopic, but a
few are over 3 feet
• Bilateral symmetry, cylindrical body
tapered at both ends, no segmentation
Characteristics cont
• No cilia or flagella
• Mostly dioecious, (male and female
reproductive organs in separate
organisms of the species)
• female larger
What system takes up most of
the organism’s body?
Characteristics cont
• Most nematodes are free-living and are
found in virtually all habitats, but
mostly in soil and fruits.
• Some are parasitic
Plant
Nematode
Characteristics cont
• Have a complete
digestive system
consisting of a
mouth, muscular
pharynx, nonmuscular intestine
(only one cell layer
thick), and an anus.
4 parts of a complete
digestive system
Quick Review Questions
1. What type of body cavity do
nematodes have?
2. What type of symmetry do they have?
3. What does the term “dioecious” mean?
4. Where can you find nematodes?
5. Do they have a digestive system?
a. Explain.
Feeding
• Many free-living roundworms use
grasping mouthparts and spines to catch
and eat other small animals.
Respiration, Circulation and
Excretion
• Roundworms exchange gases and
excrete metabolic waste through their
body walls.
• They depend on diffusion to carry
nutrients and waste through their
bodies.
Movement
• Fluid in the pseudocoelom and muscles
extending the length of their bodies
function as a hydrostatic skeleton.
• Aquatic roundworms contract muscles
to move like snakes through the
water.
• Soil-dwelling roundworms push their
way through the soil by thrashing
around.
Reproduction
• Roundworms reproduce sexually.
• Most species have separate sexes.
• Parasitic roundworms often have life
cycles that involve two or three
different hosts or several organs within
a single host.
Questions
6. What do nematodes use their
mouthparts for?
7. How do nematodes breathe?
8. How do nematodes move?
9. How do nematodes reproduce?
Discussion
• Explain why being a pseudocoelomate is
a big advancement for nematodes.
(Make reference to a previous phylum
we have studied and connect the
reference to nematodes.)
• Explain the difference between being a
hermaphrodite and being dioecious.
Discuss these differences.
• Explain why nematodes can have a
mouth and an anus and still be
considered a protostome.
Nematode hatching
A Marine Nematode
Parasitic
Nematodes
Foldable
*3 sheets
of paper
*several
markers
Wuchereria spp.
Ascaris lumbricoides
Enterobius vermicularis
Necator americanus
Trichinella spiralis
PARASITIC NEMATODES
Roundworms and Human
Disease
Ascaris
• Ascaris lumbricoides is a serious parasite of
humans and many other vertebrate animals.
• It absorbs digested food from the host’s
small intestine.
Ascarids taken from children of one village.
Ascaris Dissection
• http://www.youtube.com/watch?v=a7RA
oJ_2W5g
• Sexual dimorphism: physical characteristics that are
used to differentiate males from females
• 2 ways to tell males from females:
– Males are smaller
– Males have a coiled hook at posterior end for
copulation
Dissected Female
Monsters Inside Me…Ascaris
Coughing up worms Ascaris
• http://www.youtube.com/watch?v=N0hY
4_MMxM4 Monsters Inside Me
• http://www.youtube.com/watch?v=421
WAV98aq0 Ascaris lumbricoides
human parasite
Ascaris lumbricoides
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Giant intestinal roundworm
Ascariasis is the disease you get from the worm
Aka Hand to mouth disease
Largest roundworm a human can get (up to 16 inches)
• Begins life as free living eggs in soil
• 800 million throughout the world are infected
• Live in small intestine of humans
• Produce large # of eggs that exit with feces
• Internal anatomy is mainly reproductive organs & digestive tract
• 2nd stage larvae is the infective stage
• Human ingests embryonated eggsthey hatch in the intestinelarvae
penetrate intestinal wall & are carried via circulation to lungsmolt 2x
in lungsmigrate up trachea & are swallowed
• Worms attain sexual maturity in the
intestine, mate & begin egg production
• Infection in US is rare – worm is brought over
by people returning from vacation
• Adult worms can live in intestinal tract for
years undetected
• Can grow up to 16 inches long
• In undeveloped/unsanitary African countries
95% of the population is infected
Life cycle
Trichinella
• Adult Trichinella worms live and mate in
the intestines of their hosts.
• Larvae travel through the bloodstream
and burrow into organs and tissues.
Encysted juveniles
Muscle tissue
50 µm
Trichinella cont
•Trichinella completes its life cycle only
when another animal eats muscle tissue
containing these cysts.
•Humans can get trichinosis by eating
raw or incompletely cooked pork.
Cysts in Contaminated Pork
Trichinella spiralis
Trichinella
Trichinella spiralis
• Porkworm
• Live in mucosa of small intestine of humans &
other carnivores & omnivores (the pig)
• In intestine, adult females give birth to young
larvae that enter the circulatory system & are
carried to skeletal (striated) muscle of same
host young larvae encyst in skeletal muscles &
remain
• Another host must ingest infective meat
(muscle) to continue the life cycle
• Humans get it by eating improperly cooked pork
• Once ingested, larvae excyst in stomach & make
their way to the small intestine where they molt
4x & develop into adults
Hookworms
Necator americanus..American hookworm
• Hookworm eggs hatch and develop in the
soil.
• They use sharp toothlike plates and
hooks to burrow into the skin and enter
the bloodstream.
Hookworms cont
•Hookworms travel through the blood of their
host to the lungs and down to the intestines.
•There, they suck the host’s blood, causing
weakness and poor growth.
Small hookworms
Monsters…Flesh-eating Hookworms
Hookworm.. healthbyte
• http://www.youtube.com/watch?v=IMID
IAUBF8Y
• Hookworm relationships:)
• http://www.youtube.com/watch?v=wxGw
vE8ytCQ
HOOKWORM
*Filariaform=threadlike
*this is NOT a filarial worm
Necator americanus
• New World Hookworm/American Hookworm
• Found in Southern US
• Adults live in small intestine where they hold
onto the intestinal wall w/teeth & feed on blood
and tissue fluid
• Females can produce 10,000 & eggs daily, which
can pass out of the body in feces
• Egg hatches on warm, moist soil
• Humans can became infected with a filaria-form
larva penetrates the skin & usually between toes
• Outside defecation & subsequent walking
barefoot are methods of becoming infected
Hookworms
• Mild symptoms: rash, mild diarrhea
• Severe symptoms: anemia, weight loss
• Common in areas with warm temp & decent amount of
rainfall
• Tx: 1-3 days of meds to eliminate worms
• Recheck stool to make sure worms are gone
• Different species of HW for different hosts
• Human hookworm secretes enzymes to break down
the thick skin on the foot
• 30,000 cases of hookworm each year in the US
• Infects 1.5 billion people worldwide
• Can cause heart failure, anemia & malnutrition (not
getting enough nutrients)
Filiarial Worms
• Filarial worms are threadlike worms
that live in the blood and lymph vessels
of birds and mammals.
• They are transmitted by mosquitoes.
• Causes Elephantiasis
Filarial worm in cow eye
Elephantiasis
Elephantiasis cont
Monsters Inside Me .. Filarial
worms
• http://animal.discovery.com/tvshows/monsters-inside-me/videos/the40-year-parasite.htm
Filaria- causes, symptoms, etc.
Elephantiasis
Filariasis Treatment.. India
Filarial Worm Life Cycle
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Wuchereria spp.
Filarial worms
In tropical countries
250+ million humans infected
Wuchereria bancrofti & Wuchereria malayi
Fluid in connective tissue accumulates in peripheral
(outer) tissuesenlargement of various appendages =
elephantiasis
• Transmitted by mosquitoes
• Microfilariae-tiny worms passed between vectors
• Prevalent filarial worm in the US is Dirofilaria immitis
– Since these adult worms live in the heart and large arteries
of the lungs, the infection is called heartworm disease
– Hard to eliminate
– Condition can be fatal
– Prevention – heartworm meds
Wuchereria spp.
• Filariasis – info & treatment
• Lymphatic system blockage causes excessive
swelling
• 120 million ~ Africa, India, South Asia, Pacifica
• 25 million Indian people alone
• Noninvasive treatment
• 14 days inpatient
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1. wash w/ medicated soap
2. submerge in solution
3. antibiotic cream
4. yoga
5. massage
6. wrap in compression
• Continue treatment at home for 6 months
• 50% reduction in swelling
• Strict vegetarian diet
3 stages of infection for
lymphatic filariasis
• 1. ASYMPTOMATIC
– Shows no symptoms
• 2. INFLAMMATORY (Acute)
– Body elicits an inflammatory response
– Swelling begins
• 3. OBSTRUCTIVE (Chronic)
– Key feature: scarring of skin
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Obvious elephantiasis is present
Enterobius
vermicularis…PINWORMS
• http://www.youtube.com/watch?v=6M_
bBOSV67Y colonoscopy
• http://www.youtube.com/watch?v=R0S7
nsCVg7E&list=LPI1aJa6N7ACI&index=7
&feature=plcp Meducational
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http://www.youtube.com/watch?v=Zrn7
jTqKBFs&feature=BFa&list=LPI1aJa6N7
ACI
case study
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Enterobius vermicularis
Human pinworm aka threadworm (UK)
Most common roundworm parasite
Adults become established in lower part of large intestine
@ night, females migrate out to opening of anus
& deposit eggs containing 1st stage larva & die
Females & eggs produce an itching sensation
Easily spread because scratching an itch contaminates the
hands & bed clothes/sheets
When hands touch mouth & eggs are swallowed, the eggs
hatch
Larvae molt 4x in the small intestine & migrate to large
intestine
Adults mate & females soon begin egg production
• Small – thin- white – roundworm
• Can affect all people
• Common among children, institutionalized
persons & household members of persons
w/pinworm infection
• Treatable with OTC (over the counter) or
rx (prescription) meds
• Reinfection, which occurs easily, should be
prevented
• Can do scotch tape test to check for
infestation
• Pinworms are not usually a serious situation
Lifecycle of a Pinworm
NEMATODES & INSECTS
BENEFICIAL NEMATODES?!!
Isn’t than an oxy moron?
• http://www.ladybug.uconn.edu/factshee
ts/tp_05_nematode.html
• http://oardc.osu.edu/nematodes/
• http://oardc.osu.edu/nematodes/biology
ecology.htm
Ascaris Dissection and
Nematodes Slideshow
• http://www.studyblue.com/#file/view/5
42000
Nematoda
Quiz
In roundworms, the body cavity
that forms between the
endoderm and mesoderm is
the
a. ganglion.
b. hydrostatic skeleton.
c. pseudocoelom.
d. coelom.
All of the following are
parasitic roundworms
EXCEPT
a. Tapeworms
b. filarial worms
c. Hookworms
d. ascarid worms
Characteristics of roundworms
include a digestive system
with
a. one opening and a pseudocoelom.
b. one opening but no pseudocoelom.
c. two openings and a pseudocoelom.
d. two openings but no pseudocoelom.
Gas exchange and excretion
of metabolic wastes in
roundworms occurs
a. via a complex system of alveoli.
b. through their body walls by
diffusion.
c. through excretory tubules.
d. by flame cells.
The roundworms called
ascarids cause harm by
a. causing serious body swelling.
b. burrowing into body tissues and
causing pain.
c. causing malnutrition.
d. causing internal bleeding.
In roundworms, the body cavity
that forms between the
endoderm and mesoderm is
the
a. ganglion.
b. hydrostatic skeleton.
c. pseudocoelom.
d. coelom.
All of the following are
parasitic roundworms
EXCEPT
a. Tapeworms
b. filarial worms
c. Hookworms
d. ascarid worms
Characteristics of roundworms
include a digestive system
with
a. one opening and a pseudocoelom.
b. one opening but no pseudocoelom.
c. two openings and a pseudocoelom.
d. two openings but no pseudocoelom.
Gas exchange and excretion
of metabolic wastes in
roundworms occurs
a. via a complex system of alveoli.
b. through their body walls by
diffusion.
c. through excretory tubules.
d. by flame cells.
The roundworms called
ascarids cause harm by
a. causing serious body swelling.
b. burrowing into body tissues and
causing pain.
c. causing malnutrition.
d. causing internal bleeding.